1. Field of the Invention
The present invention relates to a method for etching. The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. Note that in this specification, a semiconductor element itself or a device including a semiconductor element is referred to as a semiconductor device. A semiconductor device includes a liquid crystal display device and the like.
2. Description of the Related Art
In resent years, semiconductor devices have been necessary for human life. Semiconductor elements such as thin film transistors included in such semiconductor devices are manufactured by forming a thin film over a substrate and processing the thin film into a desired shape by etching or the like. Such a manufacturing method is applied to liquid crystal display devices (e.g., liquid crystal televisions), for example.
In thin film transistors of conventional liquid crystal televisions, amorphous silicon films are often used as semiconductor films. This is because structures of thin film transistors formed of amorphous silicon films are thought to be manufactured with relative ease.
However, when the current circumstances of moving images (e.g., watching movies and sports in 3D) is taken into account, sharpness of moving images in a liquid crystal television using amorphous silicon films is insufficient; therefore, thin film transistors having high carrier mobility which responds at high speed are under development. For this reason, microcrystalline silicon films have been developed (e.g., Patent Document 1).